1. Field of the Invention
Exemplary aspects of the present invention relate to a toner conveyance device and an image forming apparatus, and more particularly, to a toner conveyance device for conveying toner and an image forming apparatus including the toner conveyance device.
2. Description of the Related Art
Related-art image forming apparatuses, such as copiers, facsimile machines, printers, or multifunction printers having at least one of copying, printing, scanning, and facsimile functions, typically form an image on a recording medium (e.g., a transfer sheet) according to image data. Thus, for example, a charger uniformly charges a surface of an image carrier; an optical writer emits a light beam onto the charged surface of the image carrier to form a latent image on the image carrier according to the image data; a development device supplies toner to the latent image formed on the image carrier to make the latent image visible as a toner image; the toner image is directly transferred from the image carrier onto a recording medium or is indirectly transferred from the image carrier onto a recording medium via an intermediate transfer member; a cleaner then collects residual toner not transferred and remaining on the surface of the image carrier after the toner image is transferred from the image carrier onto the recording medium; finally, a fixing device applies heat and pressure to the recording medium bearing the toner image to fix the toner image on the recording medium, thus forming the image on the recording medium.
The cleaner may include a toner conveyance device in which a conveyance screw including a helical blade rotates and conveys the toner collected by the cleaner from the surface of the image carrier in an axial direction of the conveyance screw. However, in such toner conveyance device, the toner may build up inside a toner conveyance path and clog the toner conveyance path. To address this, the toner conveyance device may include an agitator for swingingly contacting the conveyance screw in coordination with rotation of the conveyance screw so as to agitate the toner contained in the toner conveyance device and prevent clogging of the toner conveyance device.
FIGS. 1, 2A, and 2B illustrate a toner conveyance device 130V including an agitator 16V as an example of such agitator. FIG. 1 is a perspective view of the toner conveyance device 130V. FIGS. 2A and 2B illustrate a sectional view of the toner conveyance device 130V seen from a direction S in FIG. 1. The toner conveyance device 130V includes a conveyance screw 131V including a helical blade 131Vb fixedly mounted on a shaft 131Va. When the conveyance screw 131V rotates in a rotation direction R, the conveyance screw 131V conveys toner in a toner conveyance direction C. The agitator 16V includes a cantilevered plate member formed of a flexible material, with a fixed end and a free end. The free end of the cantilevered plate member includes a plurality of comb teeth 160V. The comb teeth 160V bend in coordination with rotation of the conveyance screw 131V, that is, the comb teeth 160V move reciprocally between a bent position at which the comb teeth 160V are contacted and pushed up by a helical outer circumferential surface 131Vt of the blade 131Vb of the conveyance screw 131V as illustrated in FIG. 2A, and a straight position at which the comb teeth 160V enter a helical gap of the blade 131Vb as illustrated in FIG. 2B. The comb teeth 160V swing in a direction M as the conveyance screw 131V rotates, and thus, a distance D between the tips of the comb teeth 160V and the surface of the shaft 131Va of the conveyance screw 131V fluctuates within a predetermined range.
When the comb tooth 160V is contacted and bent by the blade 131Vb as illustrated in FIG. 2A, a lower surface 160Va, not a front edge surface 160Vt, of the comb tooth 160V contacts the blade 131Vb. As noted above, as the conveyance screw 131V rotates, the comb tooth 160V enters the helical gap of the blade 131Vb as illustrated in FIG. 2B. As the conveyance screw 131V rotates further, the comb tooth 160V is contacted and bent by the blade 131Vb again as illustrated in FIG. 2A.
However, before the blade 131Vb contacts the lower surface 160Va of the comb tooth 160V, the blade 131Vb contacts an upstream edge surface 160Vs of the comb tooth 160V. Accordingly, the free end of the comb tooth 160V is bent downstream in the toner conveyance direction C and twisted. As the conveyance screw 131V continues to rotate and the comb tooth 160V resumes its original untwisted shape, and the blade 131Vb contacts the lower surface 160Va of the comb tooth 160V, the blade 131Vb hits the comb tooth 160V, generating noise.